Displays or printing devices, hereinafter image output devices, have been utilized to output color image data. These image output devices respectively have unique varying color ranges for reproduction due to differences of data output methods or systems. For example, monitors are able to reproduce a vivid color image or chromatic image because the monitors adopt an additive color mixing using light to reproduce colors. On the other hand, printers, in general, have difficulty in reproducing an image with higher luminosity and color, and have a narrower color reproduction region compared with the monitors because the printers utilize a subtractive color mixing in which colored materials, such as toner and ink, are layered.
As explained above, color reproduction regions vary according to the type of image output device. Therefore, when different types of image output devices execute an output process for the same image data, for example, when a colored image displayed on a monitor is to be output by a printer, there is likelihood that some colors may not be output with either of the image output devices. To solve the difficulty, it is necessary to convert these colors which are not able to be output into other colors which are possible for reproduction.
In order to deal with the above difficulty, an image processing device has been used by which input image data generated in a color reproduction region at an input side is copied to a color reproduction region at an output side and then converted to image data for outputting. For example, a color image processing method is known in which input color signals are compressed, copied, and converted into output color signals based on differences of color reproduction regions where the color reproduction region for the output color signals are relatively narrower than the color reproduction regions for the input color signals.
People have different color sensitivities. However, the color image processing method described above uniformly copies, compresses, and converts all the input color signals into the output color signals with a given ratio of compression. Due to the uniform ratio, such a method may reproduce images that are generally acceptable to all users.
However, there is a need for a new image processing device in which the color converting process is based on a user's subjective preference (or user's sensitivities).